ABSTRACT
Long COVID-19 is defined as persistency of symptoms, such as exertional dyspnea, twelve weeks after recovery from SARS-CoV-2 infection;its pathophysiology still needs to be fully understood. We investigated exercise tolerance and ventilatory efficiency using cardiopulmonary exercise testing (CPET) in patients with long COVID-19. Methods. One hundred patients admitted to our hospital from March to August 2020 for a moderate to critical COVID-19 were enrolled in our long COVID-19 program. Medical history, physical examination and chest HRCT were obtained at hospitalization (T0), at 3 (T3) and 15 months (T15). All HRCTs were revised using a semiquantitative CT severity score (Pan, F. et al. Radiology 2020;295(3):715-721). Pulmonary function tests (PFTs) were obtained at T and T . CPET was performed at T15 in twenty patients (10 male/10 female;mean age 62 years) with residual respiratory symptoms (e.g., exertional dyspnea) and/or an impairment in PFTs, DLCO and/or KCO . Results. At CPET, peak oxygen uptake (VO2 -peak) and ventilatory efficiency (VE /VCO2 slope) were 95.9+/-18.4 SD %pred and 31.4+/-3.9 SD, respectively. Of notice, significant correlations between VE/V'CO2 slope and CT score (T0 ) (r=0.403;p=0.039), CT score (T3) (r=0.453;p=0.022) and DLCO (T3 ) (r=-0.465;p=0.019) were observed. Conclusions. At fifteen-months from COVID-19 pneumonia, a significant number of subjects (20%) still complains of exertional dyspnea. At CPET this may be explained by reduced ventilatory efficiency (i.e., increase in VE/VCO2), possibly related to the degree of lung parenchymal involvement in the COVID-19 acute phase, likely reflecting a damage in the interstitial/pulmonary capillary structure.